Measurements in recent years of the rate of acceleration of the universe's expansion, and of the density of "dark energy" believed to be driving it, hinge on observations of type Ia supernovae (SNe Ia). The Nearby Supernova Factory (SNfactory) will produce flux-calibrated spectrophotometry of 300 SNe Ia in the local universe (0.03 < z < 0.08). This new data set will greatly increase the number of SNe Ia available for cosmological measurements in this redshift range, reducing statistical uncertainties on cosmological parameters.